The temperature selector dial in my 2001 Z3 Roadster also binds. It stops at the vertical point, but if I nudge it a few times it goes over the "hump" and continues to the maximum position. Once it's there, it will freely move from full minimum to full max with no binding. Is there a way to squirt some lubricant into the cable? If necessary, is the cable replaceable without major take-apart issues? I suspect, from previous experience with this kind of control, that there's a kink in the inner cable.